Northwestern Garter Snake

The Northwestern Garter Snake varies more in colour and pattern than any other snake in our region. A small snake, ranging from 1 to 2 ruler lengths long, adults are black, brown, or olive in colour. This may be accented by a stripe down the back. However, the width of the stripe varies, and sometimes the stripe is missing entirely. Some individuals have stripes down the sides of the body with spots between the back and side stripes. The colours of these stripes and spots vary like the rainbow - bright yellow, red, tan, blue, white, and cream are the most common colours. The colours can appear muted because of the strongly keeled scutes (scales with a ridge running from front to back), a trait shared with all other Garter Snake species. While the belly usually is pale, some snakes have bold black or red markings. Fortunately, there is one marking that is fairly reliable and can be used to help identify the Northwestern Garter Snake - a pale upper lip.

Like the Common Garter Snake and the Western Terrestrial Garter Snake, the Northwestern Garter Snake responds to handling by releasing a smelly mix of musk and feces from its vent (the opening to the reproductive and excretory systems at the base of the tail).

Making a living

Northwestern Garter Snakes usually mate in spring after emergence from their winter dens (hibernacula). Occasionally, these snakes have been observed mating in the autumn. Northwestern Garter Snakes are live-bearing, that is, the young develop inside their mothers’ body and are born fully developed. Females give birth to between 3 and 20 live young sometime around July, August or September.

Because of their small size, Northwestern Garter Snakes can be an easy (if stinky) meal for a number of predators such as birds of prey and weasels. However, it appears that Northwestern Garter Snakes have learned to make the most of their variable colouration. Studies show that brightly striped snakes flee when faced with a predator. The snake’s stripes make it difficult to tell exactly what direction and how fast it is moving. This confuses the predator and increases the chance of escape. In comparison, spotted and faintly striped garter snakes use their camouflage. By remaining motionless, the snake avoids detection.

What’s for dinner?

Northwestern Garter Snakes are fairly inactive snakes that feed during the day. Their laid-back life-style works for them just fine, however, because most of the food they eat is even more sedentary than they are! These snakes mostly eat slugs and earthworms, along with the occasional snail and small amphibian. Once adults reach a certain size, and their mouth is large enough, they also eat any eggs they find.

Places and spaces

Northwestern Garter Snakes are found in southwestern B.C. as far inland as Manning Park, and on many of the coastal islands including Vancouver Island. Northwestern Garter Snakes need two kinds of habitats: summer feeding and breeding areas, and winter dens to hibernate in (hibernacula). They like damp, heavily vegetated areas, including meadows, edge of forests, estuaries, and beaches. Unlike other garter snakes in B.C., however, they are not very aquatic, rarely entering the water. They also can be found in roadside vegetation, in weedy urban areas, and by cabins and old homesteads where they use old boards and other litter for cover. Their hibernacula usually consist of a rocky bank or fissured rocks near their summer range.

Past, present, and…future?

The Northwestern Garter Snake is very common within its range. It often outnumbers other snake species sharing its habitat. Because the species is secure and not at risk of extinction, the Northwestern Garter Snake currently is yellow-listed by the province of B.C., and considered not at risk by the federal Committee on the Status of Endangered Wildlife in Canada (COSEWIC).